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European Journal of Applied Sciences – Vol. 10, No. 6

Publication Date: December 25, 2022

DOI:10.14738/aivp.106.13534. Mawuli, S. E., Anthony, S., & Akintunde, D. O. (2022). Development of Asbestos-free Disc Brake Pad Using Periwinkle Shell Powder

and Coconut Shell Ash as Base Materials. European Journal of Applied Sciences, 10(6). 473-491.

Services for Science and Education – United Kingdom

Development of Asbestos-free Disc Brake Pad Using Periwinkle

Shell Powder and Coconut Shell Ash as Base Materials

Seckley Emmanuel Mawuli

Department of Mechanical Engineering

University of Mines and Technology, Tarkwa, Ghana

Simons Anthony

Department of Mechanical Engineering

University of Mines and Technology, Tarkwa, Ghana

Dahunsi Olurotimi Akintunde

Department of Mechanical Engineering

Federal University of Technology, Akure, Nigeria

ABSTRACT

Brake pads are integral part of an automobile braking system that contribute to the

full control of the vehicle. The composite materials for their production must

therefore possess adequate chemical, mechanical, physical, and thermal properties.

The development of asbestos-free disc brake pad using Periwinkle Shell (PS)

powder and Coconut Shell Ash (CSA) as reinforcement and frictional filler material

respectively is presented. This was done with a view of establishing suitability of PS

powder and CSA as replacements for asbestos which has been found to be

carcinogenic and capable of causing Asbestosis and Mesothelioma [1]. Other

ingredients used are graphite as lubricant, epoxy resin as binder, copper, zinc, and

aluminum powders as abrasives and also to impact mechanical strength. The

optimum percentage formulation of these materials for the pad was arrived at by

using the ANOVA tool of the Box-Behnken technique of Design Expert Software, DX- 13. The CSA and PS powders were sieved into grades of 106 μm, 150 μm, 212 μm

and 300 μm and then combined with other constituents to produce the brake pad.

The pads were characterized in terms of their physical, mechanical and tribological

properties. It was observed that increase in particle size distributions leads to

decrease in densification and carbon crosslinking of the produced composite brake

pads. Therefore, the 106 μm particle size sample has better properties than others.

Comparison analysis shows that the performance parameters of the 106 μm size

brake pad compares well, and in some cases better, with typical after-market

replacement pads, an asbestos-based brake pad and brake pads developed from

past research works.

Keywords: Brake pad, asbestos, periwinkle shell powder, coconut shell ash, Design

Expert (DX-13), physical, mechanical and tribological properties.

INTRODUCTION

The braking system is an indispensable component of an automobile, and is composed of many

parts including brake pads, master cylinder, wheel cylinders, and a hydraulic control system

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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 6, December-2022

Services for Science and Education – United Kingdom

[2]. The brake pad, itself, is an important part of the braking system allowing gears to be

changed as in automatic transmissions; and helping to slow down a vehicle or stop the vehicle

completely or to hold the vehicle stationary after it has come to a complete stop. During the

application of brake, friction between brake pads and rotating disc causes the vehicle to stop

by converting kinetic energy of the vehicle into heat energy. The brake pad assembly consists

of steel backing plates with friction materials bound to the surface facing the brake disc [3].

Brake pads are designed for friction, stability, durability and minimization of noise and

vibration.

Brake pad material is a heterogeneous substance composed of different elements. Each

constituent element has its own functions which include to improve frictional properties at low

and high temperature, reduce noise, prolong life, increase strength and rigidity as well as

reduce porosity. Basically, brake pad materials generally fall into the category of organics, semi- metallic and ceramic friction materials. These materials typically comprise the following sub- components; friction additives, fillers, binder and reinforcing fibers [4]. Combined, these

groups of materials provide the developed brake pads with the necessary properties needed

for it to perform effectively.

Changes in the weight percentage or types of elements in the formulation may result to the

alteration of the chemical, mechanical and physical properties of the brake pad materials

developed [5], [6], [7] and [8]. As a result, each new formulation developed requires to be

subjected to several tests to evaluate its wear and friction properties using on–road braking

performance test as well as abrasion testing mechanism to ensure that the developed friction

pad material meets the minimum requirements of its intended use [9].

Brake pad material development has history spanning over the past 100 years. The earliest

brake pad material was woven, but in the early 1920's, moulded materials which were made of

chrysotile asbestos fibers, a plentiful mineral, were used to replace it. In the 1950's, metallic

pads that were resin–bonded were introduced, and semi–metals which contain higher amount

of metal additives were developed in the 1960s [10]. Yet, asbestos continue to be increasingly

popular among brake pad manufacturers because of its sound absorption, its strength and

flexibility, its resistance to heat, its resistant to electrical and chemical damage and its

availability at reasonable cost [11]. However, since 1970s, the use of asbestos in brake pads has

become a source of concern It was reported that the asbestos inclusion in the commercially

graded brake pads materials is leading to cancer [12], [13], [14] and [15]. Asbestos being

carcinogenic and coupled with the problems of its disposal was therefore, banned in many

countries for use as a friction material [1]. The gradual phasing-out of asbestos as automotive

brake friction materials in many parts of the world has sparked the onset of extensive research

and development into safer alternatives and asbestos free brake pads. As a result, the brake pad

friction lining industry has seen the birth of different brake pads and shoes in the past decade,

each with its own unique composition.

Industrial and agricultural wastes are the ones currently receiving attention as alternative raw

materials to asbestos in the manufacture of brake pads [1]. Several researchers have used

different non-hazardous materials such as: lemon peel powder [16], cow bone and palm kernel

shell [17], cow hooves [18], bagasse[3], palm kernel shell and fiber [19], [20], [21], [22] and

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Mawuli, S. E., Anthony, S., & Akintunde, D. O. (2022). Development of Asbestos-free Disc Brake Pad Using Periwinkle Shell Powder and Coconut

Shell Ash as Base Materials. European Journal of Applied Sciences, 10(6). 473-491.

URL: http://dx.doi.org/10.14738/aivp.106.13534

[23], palm ash [24], rice husk and rice straw [25], maize husk [26], banana peels powder[27]

and [28]; periwinkle shell [29], [30] and [31], seashell [32], cocoa beans shell [33], palm kernel

shell, coconut shell and cashew shell [34], periwinkle shell and coconut shell [35], coconut shell

and palm kernel shell [36], sawdust composite [14], fan palm shell [32], egg shell [37] and

bamboo fibre [38] to develop brake pads. Brake pads produced from all these materials have

been evaluated for their physical, mechanical, tribological and in some cases morphological

properties; and then compared with asbestos-based brake pads. The various researchers then

concluded that the properties of their developed brake pads compared well with those of the

asbestos-based brake pads and as such can serve as replacements for asbestos in brake pad

production

The literature presented reveals that apart from the use of coconut shell powder, there is no

research into the use of Coconut Shell Ash (CSA), consecutively combination of Periwinkle Shell

(PS) powder and CSA as ingredients for the development of asbestos free brake pads. On the

other hand, work is ongoing to determine the suitability of CSA as filler material in the

construction and the rubber industries. For example, [39] conducted research into the use of

CSA as filler and Low-density Polyethylene (LDPE) plastic waste as substitution materials of

porous asphalt mixtures, where they concluded that the addition of CSA gives satisfactory

results. Similarly, [40] reviewed works done by various researchers in the use of CSA as a

cementitious material in concretes and concluded that the inclusion of CSA in concretes

increases compressive, split tensile and flexural properties with time due to its pozzolanic

nature. Based on this background, this work looks at the suitability of CSA and PS for use as

base materials in the production of brake pads.

In this work, the shell of ‘West African Tall’ coconut which is the common variety found in Ghana

is used. There is abundant production of coconut shells in Ghana, Nigeria, and other Africa

countries mainly along the coastal regions. Despite the many uses into which these shells are

put including for decoration, for jewelry, as cups and ladles, as fuel [41], and for constructional

purposes, the shells are still left as wastes that are stockpiled in open fields. Some are even

dumped into water bodies causing imbalance in the ecological system.

The type of periwinkle used in this work is Tympanotonos fuscatus (radula Linnaeus, 1758) also

known as the West Africa Mud Creeper, belonging to the family Potamididae. It is the

commonest and most dominant species of snail that thrives in the brackish waters in West

Africa. They are found in the edges of lagoons (shallow waters) [42]. This type of periwinkle

has elongated shells with regular increasing whorls, weakly curved ribs, and much fine striation

with blackish brown stripes on the shell. They can reach the size of 25 – 95 mm in length and

0.02 – 9.42 g in weight [43]. The shells of these small gastropods are agricultural wastes which

are also stockpiled in open fields in many areas where they are found causing menace to the

environment. The possible use of coconut shell and PS as an automobile brake pad material will

manage the daily generation of these two materials, to some extent.

Design of Experiments (DoE)

The Design Expert Software is a statistical tool that is utilized in screening, characterization,

and optimization of numerous effects. The design stage involved proper planning on screening

the number of factors to be considered into most required ones when faced with numerous